CHESTER Serial

This article describes the core functionality, hardware description, and example JSON message of the catalog application CHESTER Serial.

caution

Some of the basics are not provided, as they are common for all CHESTER catalog applications. Please see:

• Getting started on how to connect device to Cloud.
• Common functionality to know how LED, button and network configuration works.
• Platform Management on how to work with the interactive console.

Application Overview

CHESTER Serial is a universal application for industrial serial communications developed for the HARDWARIO CHESTER platform. It serves as a flexible gateway for integrating industrial devices (sensors, PLCs, meters) into the cloud.

The application is hardware-aware; it automatically detects the installed extension module and adapts its behavior:

• RS-232 (with Module CHESTER-X12)
• RS-485 (with Module CHESTER-X2)

Key Features

• Dual Interface Support: Automatic configuration for RS-232 (Point-to-Point) or RS-485 (Multi-drop) based on the connected hardware.
• Modbus RTU Master: Polling of up to 8 slave devices with support for standard Modbus functions.
• Transparent Mode: Bidirectional data passthrough (tunneling) without interpretation, ideal for proprietary protocols.
• Multi-Radio Connectivity: Data transmission via LTE-M / NB-IoT (CBOR) or LoRaWAN (Optimized Binary).
• Native Sensor Support: Built-in drivers for specific industrial sensors like MicroSENS (CO2), SenseCAP (Meteo), and Cubic (Particulate Matter).

Application Variants

CHESTER Serial can be ordered in one of these variants:

CHESTER Serial RS-485

The catalog application CHESTER Serial RS-485 provides RS-485/Modbus RTU connectivity.

The hardware of this application consists of the following ordering codes:

• CHESTER-M-CGLS - Standard mainboard
• CHESTER-X2 - RS-485 interface module
• CHESTER-X10 - External power input (5-28V DC)
• CHESTER-E2-LP - Enclosure with SMA pigtail

See Ordering Codes for more details.

CHESTER Serial RS-232

The catalog application CHESTER Serial RS-232 provides RS-232 connectivity for legacy devices.

The hardware of this application consists of the following ordering codes:

• CHESTER-M-CGLS - Standard mainboard
• CHESTER-X12 - RS-232 interface module
• CHESTER-E2-LP - Enclosure with SMA pigtail

See Ordering Codes for more details.

caution

CHESTER Serial requires external power supply (5-28V DC) for operation. It cannot run on battery alone.

Operating Modes

Modbus RTU Master

In this mode, CHESTER acts as a Master controller that periodically queries connected Slave devices.

• Capacity: Up to 8 devices simultaneously.
• Addressing: Supports slave addresses 1–247.
• Functions: Supports FC01, FC02, FC03, FC04, FC05, FC06, FC0F, and FC10.

Transparent Mode

CHESTER acts as a bridge. Data received from the serial port is sent to the cloud "as is" and vice versa.

• Usage: Debugging, legacy equipment, non-standard protocols.
• Limitation: Only one connected device is supported in this mode.

Technical Specifications

Feature	Value
Operating System	Zephyr RTOS
Physical Interface	RS-232 (Module X12), RS-485 (Module X2)
Application Protocols	Transparent (RAW), Modbus RTU
Cloud Formats	CBOR (LTE), Optimized Binary (LoRaWAN)
Power Supply	External source (5–28V DC) required

Integrated Sensor Drivers

The firmware includes native support for the following devices:

Device	Interface	Measurements
MicroSENS 180-HS	RS-232	CO2 (0–100%), Temperature (-40 to +85°C), Pressure (300–1100 mbar)
SenseCAP S1000 / S500	RS-485 Modbus	Air temperature, humidity, pressure, light intensity, wind speed, wind direction
CUBIC 6303	RS-485 Modbus	PM1.0, PM2.5, PM10 (in μg/m³)
Generic Modbus	RS-485 Modbus	Custom register mapping for any Modbus RTU device

Default Configuration

This is the default configuration (printed using the app config show command):

app config mode lte
app config serial-mode modbus
app config interval-sample 60
app config interval-report 900
app config serial-baudrate 9600
app config serial-parity none
app config serial-stop-bits 1
app config serial-data-bits 8

Specific Commands

info

You can easily explore the whole command tree structure - start with the help command.

caution

To apply a new configuration, you need to call config save, which applies the new configuration parameters and reboots the device.

Network Mode

Command to set communication mode (lte, lrw, or none):

app config mode <lte/lrw/none>

Serial Mode

Command to set serial operating mode (modbus or transparent):

app config serial-mode <modbus/transparent>

Intervals

Command to set sample interval in seconds:

app config interval-sample <1-86400>

Command to set report interval in seconds:

app config interval-report <30-86400>

Serial Line Configuration

Command to set baud rate:

app config serial-baudrate <1200-115200>

Command to set parity (none, odd, even):

app config serial-parity <none/odd/even>

Command to set stop bits (1 or 2):

app config serial-stop-bits <1/2>

Command to set data bits (7 or 8):

app config serial-data-bits <7/8>

Device Configuration

Command to configure a device slot (1-8):

app config device<n> "<type>,<address>,<timeout>"

Example configurations:

# SenseCAP Weather Station on address 1
app config device1 "sensecap_s1000,1,1"

# MicroSENS CO2 sensor (transparent mode)
app config device1 "microsens_180hs"

# Generic Modbus device on address 5
app config device2 "generic_modbus,5,1"

Diagnostics Commands

Command to list configured devices:

device list

Command to trigger immediate measurement:

app sample

Command to trigger immediate data transmission:

app send

Command to test Modbus communication directly:

modbus read <address> <count> <type>

Example: Read 5 input registers from slave address 1:

modbus read 1 5 input

Firmware

The latest firmware is available in the Catalog Applications Firmware chapter.

Example JSON Message

LTE

{
  "message": {
    "version": 1,
    "sequence": 42,
    "timestamp": 1673272805
  },
  "attribute": {
    "vendor_name": "HARDWARIO",
    "product_name": "CHESTER-M",
    "hw_variant": "CGLS",
    "hw_revision": "R3.4",
    "fw_name": "CHESTER Serial",
    "fw_version": "v3.0.0",
    "serial_number": "2159018267"
  },
  "system": {
    "uptime": 86400,
    "voltage_rest": 3.7,
    "voltage_load": 3.65,
    "current_load": 45
  },
  "network": {
    "imei": 351358815180770,
    "imsi": 901288910018982,
    "parameter": {
      "eest": 7,
      "ecl": 0,
      "rsrp": -85,
      "rsrq": -6,
      "snr": 12,
      "plmn": 23003,
      "cid": 939040,
      "band": 20,
      "earfcn": 6447
    }
  },
  "thermometer": {
    "temperature": 24.5
  },
  "accelerometer": {
    "accel_x": 0.05,
    "accel_y": -0.12,
    "accel_z": 9.78,
    "orientation": 2
  },
  "serial_devices": [
    {
      "slot": 1,
      "type": "sensecap_s1000",
      "address": 1,
      "measurements": {
        "air_temperature": 22.5,
        "air_humidity": 48.2,
        "air_pressure": 101250,
        "light_intensity": 850,
        "wind_speed": 3.2,
        "wind_direction": 225
      }
    },
    {
      "slot": 2,
      "type": "cubic_6303",
      "address": 2,
      "measurements": {
        "pm1_0": 12,
        "pm2_5": 18,
        "pm10": 25
      }
    }
  ]
}

LoRaWAN

{
  "voltage_rest": 3.7,
  "voltage_load": 3.65,
  "current_load": 45,
  "orientation": 2,
  "therm_temperature": 24.5,
  "devices": [
    {
      "slot": 1,
      "type": "sensecap_s1000",
      "air_temperature": 22.5,
      "air_humidity": 48.2,
      "wind_speed": 3.2,
      "wind_direction": 225
    }
  ]
}

note

Due to the 51-byte LoRaWAN payload limit, the transmitted data is highly compressed. Not all measurements may be included in a single transmission. The payload structure varies based on configured devices and their data priorities.